119 research outputs found

    Are better communicators better readers? : an exploration of the connections between narrative language and reading comprehension

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    The association between receptive language skills and reading comprehension has been established in the research literature. Even when the importance of receptive skills for reading comprehension has been strongly supported, in practice lower levels of skills tend to go unnoticed in typically developing children. A potentially more visible modality of language, expressive skills using speech samples, has been rarely examined despite the longitudinal links between speech and later reading development, and the connections between language and reading impairments. Even fewer reading studies have examined expressive skills using a subgroup of speech samples – narrative samples – which are closer to the kind of language practitioners can observe in their classrooms, and are also a rich source of linguistic and discourse-level data in school-aged children. This thesis presents a study examining the relationship between expressive language skills in narrative samples and reading comprehension after the first two years of formal reading instruction, with considerable attention given to methodological and developmental issues. In order to address the main methodological issues surrounding the identification of the optimal linguistic indices in terms of reliability and the existence of developmental patterns, two studies of language development in oral narratives were carried out. The first of the narrative language studies drew data from an existing corpus, while the other analysed primary data, collected specifically for this purpose. Having identified the optimal narrative indices in two different samples, the main study examined the relationships between these expressive narrative measures along with receptive standardised measures, and reading comprehension in a monolingual sample of eighty 7- and 8-year-old children attending Year 3 in the UK. Both receptive and expressive oral language skills were assessed at three different levels: vocabulary, grammar and discourse. Regression analyses indicated that, when considering expressive narrative variables on their own, expressive grammar and vocabulary, in that order, contributed to explain over a fifth of reading comprehension variance in typically developing children. When controlling for receptive language however, expressive skills were not able to account for significant unique variance in the outcome measure. Nonetheless, mediation analyses revealed that receptive vocabulary and grammar played a mediating role in the relationship between expressive skills from narratives and reading comprehension. Results and further research directions are discussed in the context of this study’s methodological considerations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Assessment of Nonoccupational Exposure to DDT in the Tropics and the North: Relevance of Uptake via Inhalation from Indoor Residual Spraying

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    Ba c k g r o u n d: People who live in dwellings treated with indoor residual spraying (IRS) of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] for disease–vector control in the tropics and indig-enous populations in the Arctic who comsume marine mammals experience high nonoccupational exposure to DDT. Although the use of DDT in IRS is rising, the resulting nonoccupational expo-sure is poorly characterized. ob j e c t i v e s: We have provided a comparative assessment of exposure to DDT and its metabolites in the general population of the tropical and northern regions and in highly exposed populations in these regions. Me t h o d s: We compiled > 600 average or median DDT concentrations from the peer-reviewed literature, representing > 23,000 individual measurements in humans, food, air, soil, and dust. We use Monte Carlo sampling of distributions based on these data to estimate distributions of population- and route-specific uptake. We evaluate our exposure estimates by comparing them with biomonitoring data .re s u l t s: DDT concentrations are highest in people living in IRS-treated houses and lowest in the northern general population, differing by a factor of about 60. Inuits and the general population in the tropics have similar concentrations. Inhalation exposure explains most of the difference in concentration between the highly exposed and the general population in the Tropics. Calculated exposure levels are consistent with human biomonitoring data. co n c l u s i o n s: Nonoccupational inhalation exposure is a relevant exposure pathway for people living in homes treated by IRS of DDT. Continued monitoring of time trends and DDE to DDT ratios in the Tropics and in the North is needed to identify a possible slowdown in concentration decline and the influence of ongoing DDT use.ISSN:1552-9924ISSN:0091-676

    Urban source term estimation for mercury using a boundary-layer budget method

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    Mercury is a heavy metal of particular concern due to its adverse effects on human health and the environment. Recognizing this problem, the UN Minamata Convention on Mercury was recently adopted, where signatory countries agreed to reduce anthropogenic mercury emissions. To evaluate the effectiveness of the convention, quantitative knowledge on mercury emissions is crucial. So far, bottom-up approaches have successfully been applied to quantify mercury emission – especially for point sources. Distributed sources make up a large share of the emission; however, they are still poorly characterized. Here, we present a top-down approach to estimate mercury emissions based on atmospheric measurements in the city of Zurich, Switzerland. While monitoring the atmospheric mercury concentrations during inversion periods in Zurich, we were able to relate the concentration increase to the mercury emission strength of the city using a box model. By means of this boundary-layer budget approach, we succeeded in narrowing down the emissions of Zurich to range between 41±8&thinsp;kg&thinsp;a−1 (upper bound) and 24±8&thinsp;kg&thinsp;a−1 (lower bound). Thereby, we could quantify emissions from mixed, diffuse and point-like sources and derive an annual mercury per capita emission of 0.06 to 0.10&thinsp;g&thinsp;a−1. The approach presented here has the potential to support authorities in setting up inventories and to validate emission estimations derived from the commonly applied bottom-up approaches. Furthermore, our method is applicable to other compounds and to a wide range of cities or other areas, where sources or sinks for mercury and other atmospheric pollutants are presumed.</p

    Dirichlet sigma models and mean curvature flow

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    The mean curvature flow describes the parabolic deformation of embedded branes in Riemannian geometry driven by their extrinsic mean curvature vector, which is typically associated to surface tension forces. It is the gradient flow of the area functional, and, as such, it is naturally identified with the boundary renormalization group equation of Dirichlet sigma models away from conformality, to lowest order in perturbation theory. D-branes appear as fixed points of this flow having conformally invariant boundary conditions. Simple running solutions include the paper-clip and the hair-pin (or grim-reaper) models on the plane, as well as scaling solutions associated to rational (p, q) closed curves and the decay of two intersecting lines. Stability analysis is performed in several cases while searching for transitions among different brane configurations. The combination of Ricci with the mean curvature flow is examined in detail together with several explicit examples of deforming curves on curved backgrounds. Some general aspects of the mean curvature flow in higher dimensional ambient spaces are also discussed and obtain consistent truncations to lower dimensional systems. Selected physical applications are mentioned in the text, including tachyon condensation in open string theory and the resistive diffusion of force-free fields in magneto-hydrodynamics.Comment: 77 pages, 21 figure

    Ergebnis der selektiven Verpaarung beim Entlebucher Sennenhund zur Reduktion der ureteralen Ektopie

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    Outcome of selective mating in the Entlebucher Mountain Dog for reduction of ureteral ectopia The Entlebucher Mountain Dog is predisposed to ureteral ectopia and associated diseases of the urinary tract as well as the kidneys, which can have severe to lethal consequences. Due to the clustered occurrence of clinical signs in 11 % of Entlebucher Mountain dogs in the absence of a genetic test for ureteral ectopia, screening was introduced in 2008 to allow phenotype-based breeding selection. The ureteral orifices of the dogs are visualized by ultrasound and existing urinary retention or urinary incontinence is documented. The diagnostic findings were evaluated centrally with assignment to one of five phenotypes depending on the localization of the ureteral orifices and the renal and ureteral shape. Breeding approval and mating restrictions are the responsibility of the respective breeding associations and predominantly Entlebucher Mountain Dogs with extravesical ectopic ureters and/or clinical signs were excluded from breeding. The effect of phenotype-based selective mating on the incidence of ureteral ectopia and its clinical signs, as well as possible factors influencing the expression of the phenotype, were determined in the birth cohorts after the introduction of screening. Analysis of the data set of 1456 phenotyped Entlebucher Mountain Dogs showed, that at 11 % versus 5 %, males were more frequently assigned to the extravesical phenotype than females. The effect of phenotype-based breeding selection was examined in a subpopulation consisting of phenotyped parents and their offspring (n = 876). The prevalence of the extravesical phenotype decreased from 24 % in the 2005 to 2007 birth cohorts to 1,4 % in the 2015 to 2017 birth cohorts. Since 2015 almost no Entlebucher Mountain Dogs with incontinence, hydroureter or hydronephrosis have been recorded. It was feared that the additional selection measures to control ureteral ectopia in the small Entlebucher Mountain Dog population would intensify the inbreeding increase. However, this has so far remained absent. Therefore, as long as no genetic test is available, it is recommended to continue phenotype-based breeding selection with exclusion of dogs with extravesical ureteral ectopia and/or hydroureter/hydronephrosis/urinary incontinence, while keeping an eye on the development of the inbreeding coefficient. Keywords: Ectopic ureter, Dog, Inbreeding, Phenotype, Breeding selection Deutsch Ergebnis der selektiven Verpaarung beim Entlebucher Sennenhund zur Reduktion der ureteralen Ektopie Der Entlebucher Sennenhund ist prädisponiert für die ureterale Ektopie und damit für assoziierte Erkrankungen der Harnwege sowie der Nieren, was schwerwiegende bis letale Folgen haben kann. Aufgrund des gehäuften Auftretens klinischer Symptome bei 11 % der Entlebucher Sennenhunde wurde in Ermangelung eines Gentests auf ureterale Ektopie 2008 ein Screening eingeführt, um eine Phänotyp-basierte Zuchtselektion zu ermöglichen. Die Uretermündungen der Hunde werden in der Regel mittels Ultraschall lokalisiert und bestehender Harnrückstau oder Harninkontinenz wird dokumentiert. Die Befundung erfolgte zentral mit einer Zuordnung zu einem von fünf Phänotypen in Abhängigkeit von der Lokalisation der Uretermündungen sowie der Nieren – und Ureterengestalt. Die Zuchtzulassung und Verpaarungsbeschränkungen obliegen den jeweiligen Zuchtverbänden, wobei überwiegend Entlebucher Sennenhunde mit extravesikal ektopischen Ureteren und/oder klinischen Symptomen von der Zucht ausgeschlossen wurden. Die Auswirkung der Phänotyp-basierten selektiven Verpaarung auf das Auftreten der ureteralen Ektopie und deren klinischen Symptome sowie mögliche Einflussfaktoren auf die Ausprägung des Phänotyps wurden in den Geburtsjahren nach Einführung des Screenings ermittelt. Die Analyse des Datensatzes mit 1456 phänotypisierten Entlebucher Sennenhunden zeigte, dass mit 11 % versus 5 % Rüden häufiger als Hündinnen dem extravesikalen Phänotyp zugeteilt wurden. Die Auswirkung der Phänotyp-basierten Zuchtselektion wurde an einer Teilpopulation, bestehend aus phänotypisierten Elterntieren und ihren Nachkommen (n = 876), untersucht. Die Prävalenz des extravesikalen Phänotyps nahm von 24 % bei den Geburtsjahren 2005 bis 2007 auf 1,4 % bei den Geburtsjahren 2015 bis 2017 ab. Seit 2015 wurden nahezu keine Entlebucher Sennenhunde mehr mit Inkontinenz, Hydroureter oder Hydronephrose erfasst. Befürchtet wurde, dass die zusätzlichen Selektionsmassnahmen zur Bekämpfung der ureteralen Ektopie in der kleinen Entlebucher Sennenhundepopulation den Inzuchtanstieg verstärken würde. Dies blieb bisher jedoch aus. Daher wird, solange kein genetischer Test zur Verfügung steht, empfohlen, die Phänotyp-basierte Zuchtselektion mit Ausschluss von Hunden mit extravesikaler ureteraler Ektopie und/oder Hydroureter/Hydronephrose/Harninkontinenz vorerst weiterzuführen und gleichzeitig die Entwicklung des Inzuchtkoeffizienten im Auge zu behalten. Schlüsselwörter: Ektopischer Ureter, Hund, Inzucht, Phänotyp, Zuchtselektion Français Résultat de l’accouplement sélectif chez le bouvier de l’Entlebuch pour réduire l’ectopie urétérale Le Bouvier de l’Entlebuch est prédisposé à l’ectopie urétérale et aux maladies associées des voies urinaires ainsi que des reins, ce qui peut entraîner des conséquences fatales. En raison de l’apparition de signes cliniques chez 11 % des chiens et en l’absence d’un test génétique pour l’ectopie urétérale, un dépistage a été introduit en 2008 pour permettre une sélection d’élevage basée sur le phénotype. Les orifices urétraux des chiens ont été visualisés par échographie et la rétention ou l’incontinence urinaire existante documentée. Les résultats du diagnostic ont été évalués de manière centralisée avec attribution à l’un des cinq phénotypes en fonction de la localisation des orifices urétéraux ainsi que de la forme des reins et des uretères. L’approbation pour la reproduction et les restrictions d’accouplement relèvent de la responsabilité des associations d’élevage respectives et les bouviers de l’Entlebuch présentant des uretères ectopiques extravésicaux et/ou des signes cliniques ont majoritairement été exclus de la reproduction. L’effet de cet accouplement sélectif basé sur le phénotype sur l’incidence de l’ectopie urétérale et de ses signes cliniques ainsi que les facteurs possibles influençant l’expression du phénotype ont été déterminés dans les cohortes de naissance après l’introduction du dépistage. L’analyse de l’ensemble des données de 1456 Bouviers de l’Entlebuch phénotypés a montré que, à 11 % contre 5 %, les mâles étaient plus fréquemment affectés au phénotype extravésical que les femelles. L’effet de la sélection d’élevage basée sur le phénotype a été examiné dans une sous-population composée de parents phénotypés et de leur progéniture (n = 876). La prévalence du phénotype extravésical est passée de 24 % dans les cohortes de naissance de 2005 à 2007 à 1,4 % dans les cohortes de naissance de 2015 à 2017. Depuis 2015, presque aucun bouvier d’Entlebuch présentant une incontinence, un hydrouretère ou une hydronéphrose n’a été enregistré. Une possible augmentation de la consanguinité due aux mesures de sélection supplémentaires visant à contrôler l’ectopie urétérale ne s’est pas produite. Par conséquent, tant qu’aucun test génétique n’est disponible, il est recommandé de poursuivre la sélection d’élevage basée sur le phénotype avec exclusion des chiens présentant une ectopie urétérale extravésicale et/ou une hydrouretère/hydronéphrose/incontinence urinaire, tout en surveillant l’évolution du coefficient de consanguinité. Mots-clés: auretère ectopique, chien, consanguinité, phénotype, sélection d’élevage Italiano Risultato dell'accoppiamento selettivo nel cane da montagna Entlebuch per ridurre l'ectopia ureterale Il bovaro dell’Entlebuch è predisposto all’ectopia ureterale e quindi alle malattie che sono correlate al tratto urinario e renale con possibili conseguenze letali. A causa della frequente comparsa di segni clinici nell’11 % dei cani e in assenza di un test genetico per l’ectopia ureterale, nel 2008 è stato introdotto uno screening per consentire la selezione fenotipica dei riproduttori. Gli orifizi ureterali dei cani sono solitamente localizzato tramite ecografia e viene documentata la presenza di ritenzione o incontinenza urinaria. I risultati sono stati valutati in modo centralizzato e si è assegnato il risultato a uno dei cinque fenotipi a seconda della localizzazione degli orifizi ureterali e della forma dei reni e degli ureteri. L’autorizzazione all’allevamento e le restrizioni all’accoppiamento sono di competenza delle rispettive associazioni di allevatori e i bovari dell’Entlebuch con ureteri ectopici extravescicali e/o con segni clinici sono stati prevalentemente esclusi dalla riproduzione. L’effetto dell’accoppiamento selettivo, basato sul fenotipo per rapporto all’incidenza dell’ectopia ureterale e dei suoi segni clinici, nonché dei possibili fattori che influenzano l’espressione del fenotipo, è stato determinato nelle coorti di nascita dopo l’introduzione dello screening. L’analisi del set di dati di 1456 bovari dell’Entlebuch fenotipizzati ha dimostrato che, con una percentuale dell’11 % rispetto al 5 %, i maschi erano più frequentemente assegnati al fenotipo extravescicale rispetto alle femmine. L’effetto della selezione riproduttiva basata sul fenotipo è stato esaminato in una subpopolazione composta da genitori fenotipizzati e dalla loro discendenza (n = 876). La prevalenza del fenotipo extravescicale è diminuita dal 24 % nelle coorti di nascita dal 2005 al 2007 all’1,4 % nelle coorti di nascita dal 2015 al 2017. Dal 2015 non sono stati registrati quasi più bovari dell’Entlebuch con incontinenza, idrouretere o idronefrosi. Non si è riscontrato un possibile aumento della consanguineità dovuto alle misure di selezione aggiuntive per controllare l’ectopia ureterale. Pertanto, finché non è disponibile un test genetico, si raccomanda di continuare la selezione fenotipica con l’esclusione dei cani con ectopia ureterale extravescicale e/o idrouretere/idronefrosi/incontinenza urinaria, facendo particolare attenzione all’andamento del coefficiente di consanguineità. Parole chiavi: Uretere ectopico, cane, consanguineità, fenotipo, selezione riproduttiv

    Helicoidal surfaces rotating/translating under the mean curvature flow

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    We describe all possible self-similar motions of immersed hypersurfaces in Euclidean space under the mean curvature flow and derive the corresponding hypersurface equations. Then we present a new two-parameter family of immersed helicoidal surfaces that rotate/translate with constant velocity under the flow. We look at their limiting behaviour as the pitch of the helicoidal motion goes to 0 and compare it with the limiting behaviour of the classical helicoidal minimal surfaces. Finally, we give a classification of the immersed cylinders in the family of constant mean curvature helicoidal surfaces.Comment: 21 pages, 22 figures, final versio

    Phylogenetic Analysis of Seven WRKY Genes across the Palm Subtribe Attaleinae (Arecaceae) Identifies Syagrus as Sister Group of the Coconut

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    BACKGROUND:The Cocoseae is one of 13 tribes of Arecaceae subfam. Arecoideae, and contains a number of palms with significant economic importance, including the monotypic and pantropical Cocos nucifera L., the coconut, the origins of which have been one of the "abominable mysteries" of palm systematics for decades. Previous studies with predominantly plastid genes weakly supported American ancestry for the coconut but ambiguous sister relationships. In this paper, we use multiple single copy nuclear loci to address the phylogeny of the Cocoseae subtribe Attaleinae, and resolve the closest extant relative of the coconut. METHODOLOGY/PRINCIPAL FINDINGS:We present the results of combined analysis of DNA sequences of seven WRKY transcription factor loci across 72 samples of Arecaceae tribe Cocoseae subtribe Attaleinae, representing all genera classified within the subtribe, and three outgroup taxa with maximum parsimony, maximum likelihood, and Bayesian approaches, producing highly congruent and well-resolved trees that robustly identify the genus Syagrus as sister to Cocos and resolve novel and well-supported relationships among the other genera of the Attaleinae. We also address incongruence among the gene trees with gene tree reconciliation analysis, and assign estimated ages to the nodes of our tree. CONCLUSIONS/SIGNIFICANCE:This study represents the as yet most extensive phylogenetic analyses of Cocoseae subtribe Attaleinae. We present a well-resolved and supported phylogeny of the subtribe that robustly indicates a sister relationship between Cocos and Syagrus. This is not only of biogeographic interest, but will also open fruitful avenues of inquiry regarding evolution of functional genes useful for crop improvement. Establishment of two major clades of American Attaleinae occurred in the Oligocene (ca. 37 MYBP) in Eastern Brazil. The divergence of Cocos from Syagrus is estimated at 35 MYBP. The biogeographic and morphological congruence that we see for clades resolved in the Attaleinae suggests that WRKY loci are informative markers for investigating the phylogenetic relationships of the palm family
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